The invention relates to an operating theater luminaire having at least one discharge lamp which can be switched on and off, according to the preamble of Patent claims 1 and 3.
Many operating theater luminaires which work with the aid of discharge lamps are known (see, for example, U.S. Pat. No. 5,861,706) are known. Furthermore, it is already known for discharge lamps to be combined with incandescent lamps in a luminaire body (DE-A 31 39 425, EP-B 819 836, DE-A 36 11 138, DE-A 195 05 925).
Operating theater luminaires having incandescent lamps have the disadvantage that the development of heat inside the luminaire body is considerable, and this not only signifies an increased power consumption, but also is attended by the problem that the heat produced inside the luminaire body must be dissipated.
By contrast, the efficiency of discharge lamps is substantially higher, and their heat output is substantially reduced by comparison with that of incandescent lamps. A problem in the use of discharge lamps in operating theater luminaires consists, however, in that continuous or stepped brightness control is virtually impossible, and that in the event of failure of the discharge lamp a reserve light is available, if required, in the form of a heat-producing incandescent lamp.
Also already known is a luminaire having two high-intensity discharge lamps without electrodes (U.S. Pat. No. 5 861 706), in each case only one lamp arranged at the focal point of the reflector burning during operation, while the other is started when a short power failure comes about which causes an extinction of the discharge lamp currently alight. Since, because of its strong heating, this latter lamp cannot be immediately restarted upon subsequent restitution of the mains voltage, the second discharge lamp, arranged outside the focal point, must be started and take over at least temporarily the function of the actual operating lamp.
It is the object of the invention to create an operating theater luminaire of the generic type mentioned at the beginning in the case of which brightness control is possible in the operating area without the need for additional incandescent lamps.
The features of the characterizing part of Patent claim 1 are provided for the purpose of achieving this object.
The concept of the invention is therefore to be seen in that the brightness is controlled in the operating area by virtue of the fact that two or more discharge lamps of different power are optionally switched on. It is possible in this way to perform in the operating area brightness adjustment which, although not continuous, is stepped and entirely sufficient for practical purposes.
A preferred power grading is to be gathered from claim 2.
A further object of the invention consists in that in the event of failure of the discharge lamp currently alight, a fully usable reserve light is available for continuing the operation.
This can be performed by the measure of the characterizing part of claim 3 in the case of a luminaire both according to the preamble of claim 1 and according to that of claim 3.
By contrast with the arrangement according to U.S. Pat. No. 5 861 706, however, the additional discharge lamps of the same or different power serve the purpose of taking over the illumination of the operating area in the case that the discharge lamp currently alight has reached the end of its service life or is shortly before the end of the service life. The function of the operational discharge lamp is taken over by the other discharge lamp or taken over by one of the other discharge lamps in this case.
In the case of the embodiment according to claim 1 or 2, as well, a suitable reserve light is ensured in the case of failure of a discharge lamp. Although there is a change in the intensity of illumination in the operating area in this embodiment in the case of the replacement of a failed discharge lamp by another, located in the same housing, there is nevertheless still sufficient light available to be able to conduct to the end an operation which is underway. In this case, for example, after the failure of one discharge lamp all the discharge lamps located in the luminaire body are to be exchanged.
The development according to claim 4 is particularly advantageous, because it is thereby achieved that all the discharge lamps are worn out uniformly, with the result that it makes sense after the termination of the service life of one of the discharge lamps for all the discharge lamps to be immediately replaced by new ones, as a result of which the operating theater luminaire is once again rendered fully operational. A particular advantage of the embodiment according to claim 4 consists in that the service life is lengthened in accordance with the number of the discharge lamps used. As a result, not only is the service interval provided for exchanging a lamp doubled by up to 10 years, but a reserve light which is of a quality fully identical with the lamp light which had just been switched on is continuously available in the case of failure of one of the plurality of, in particular two discharge lamps. To be precise, it is extremely unlikely that all the plurality of discharge lamps provided in the luminaire body will fail simultaneously, with the result that upon failure of one discharge lamp the second or another one located in the luminaire body can be used to replace the failed discharge lamp in order to take over the function thereof.
The design according to claim 5 is expedient in order to avoid interruption of the luminous flux during switching over from one discharge lamp to another.
The plurality of discharge lamps can be arranged in a stationary fashion in accordance with claim 6, or be arranged in a fashion capable of being adjusted in a common reflector, according to claim 7.
There is to be provided on the luminaire a display which signals the failure of a discharge lamp, whereupon all the discharge lamps located in the luminaire body are to be replaced by new ones. This ensures the luminaire operates in an absolutely fail safe fashion even in the case of the failure of a discharge lamp, without there being an impairment of the quality of the illumination of the operating area.